A cervical biomechanical study.
We sought to demonstrate the three-dimensional (3D) intervertebral motion characteristics of the cervical spine in healthy volunteers using cone beam computed tomography (CBCT) combined with 3D-3D registration technology.
Summary of Background Data.
No previous studies have used CBCT combined with 3D-3D registration technology to successfully documented in vivo 3D intervertebral six-degrees-of-freedom (6-DOF) motions of the cervical spine.
Twenty healthy subjects underwent cervical (C1–C7) CBCT scans in seven functional positions. Segmented 3D vertebral body models were established according to the cervical CBCT images. A 3D-to-3D registration was then performed for each vertebral body in the different positions to calculate the 3D segmental motion characteristics in vivo.
During flexion–extension, the range-of-motion (ROM) of C1–C2 and C4–C5 was significantly greater than the other segments. The average coupled axial rotation and lateral bending of each segment were between 0.6° and 3.2°. The average coupling translations in all directions were between 0.2 and 2.1 mm. During axial rotation, the ROM of C1–C2 was 65.8 ± 5.9°, which accounted for approximately 70% of all axial rotation. The motion and displacement of C1–C2 coupled lateral bending were 11.4 ± 5.2° and 8.3 ± 1.9 mm, respectively. During lateral bending, the ROM of C3–C4 was significantly greater than C1–C2, C5–C6, and C6–C7. The coupled axial rotation of C1–C2 was 34.4 ± 8.1°, and the coupled lateral translation was 3.8 ± 0.5 mm. The coupled superoinferior and anteroposterior translation of each cervical segment were between 0.1 and 0.6 mm.
CBCT combined with 3D-3D registration was used to accurately measure and record the ROMs of lateral bending, axial rotation, and flexion–extension in cervical vertebrae under physiological-load conditions. Our findings may contribute to the diagnosis of cervical spinal disease, the development of new surgical techniques, and the restoration of normal, cervical segmental movement.
Level of Evidence: 3